[Libav-user] Encoding with no compression with OpenH264
muller at vki.com
Tue Mar 8 20:24:16 CET 2016
1) The user is still not happy with the resolution. He says a frame rate of 1 frame per second is too slow and he would prefer to use 10 frames per second instead. And, even at this frame rate, the quality is much lower than either libx264 or mpeg4.
2) Even though I'm unable to share the set of images, I extracted 2 png images - one for a good quality image and one for the bad quality image. I just don't know whether it's ok to attach images within this group. I assume the list administrators are monitoring this exchange. If somebody could let me know whether it's ok to attach a couple of images which are just pieces of the background to show the quality difference I'm getting please let me know.
3) I tried using just the command line to see whether I can get my parameters to generate a good h264.mp4 file. I used the following command:
ffmpeg -framerate 10 -start_number 1 -i image%02d.png -c:v h264 fr10_ffmpeg.mp4
With my 17 images, if I set a frame rate of 10, I get the following message from ffmpeg:
[libopenh264 @ 0x261d840] [OpenH264] this = 0x0x263fa90, Warning:bEnableFrameSkip = 0,bitrate can't be controlled for RC_QUALITY_MODE,RC_BITRATE_MODE and RC_TIMESTAMP_MODE without
enabling skip frame.
4) I also get the following message:
unknown side data type 10 (24 bytes)
5) Each png file is around 190K. The h264-encoded mp4 file is 454K; the mpeg4 file is 3.8M. Clearly, the mpeg4 file appears to be storing all images in more detail, while the h264 encoder is not. Using a frame rate of 1 frame/second, the h264-encoded file is 1.7M.
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